Thesis (M.Sc.)--Chulalongkorn University, 2013

Tetragonula laeviceps is one of Thai native stingless bees. A hive is composed of cells called pots, that are used to store products. The material used in the construction called cerumen is a mixture of wax and propolis. It was reported that the mixed products of bees had the better bioactivities than a single product. Here, this research was focused on the antiproliferative activity of cerumen. The cerumen was collected from Chanthaburi province and extracted by 80% methanol, dichloromethane, and hexane, respectively. Also, the reversed order of solvents was used to extract. Next, all of crude extracts were examined the in vitro antiproliferative activity against 5 human cancer cell lines by MTT assay. The cytotoxicity was determined by 50% inhibition concentration (IC50) values. The result showed that reverse crude dichloromethane extract (reCDE) presented the best cytotoxicity against 5 cancer cell lines with the IC50 values in the range of 0.56 - 5.25 µg/mL. Thus, reCDE was further purified by silica gel chromatography to give 16 fractions. By the antiproliferative assay, it showed that fraction VII and VIII exhibited the best cytotoxicity against those cell lines with the IC50 value in the range of 3.38 - 6.46 and 5.37 - 6.60 µg/mL, respectively. Both fractions were further purified by silica gel chromatography until gaining a pure compound. By Nuclear Magnetic Resonance Spectroscopy analysis, it was identified as alpha-mangostin. This compound was exhibited antiproliferative activity against BT474, Chago, Hep-G2, KATO-III and SW620 with IC50 values at 0.50, 0.92, 0.39, 0.36 and 0.62 µg/mL, respectively. While doxorubicin showed IC50 values at 0.42, 0.35, 0.32, 0.56 and 0.07 µg/mL, respectively. After cancer cell lines were treated with the isolated alpha-mangostin at IC50 concentration, cell morphology of the treated cell lines was revealed an apoptotic-like character. From this research, alpha-mangostin in T. laeviceps cerumen was a new choice to develop to be an anticancer agent.